1. Field of the Invention
The present invention relates to towing accessories and, more particularly without limitation, to tow bars for connecting a trailing or towed vehicle to a towing vehicle.
2. Description of the Related Art
A tow bar is generally used for connecting a hitch arrangement of a vehicle to be towed, sometimes referred to herein as a trailing or towed vehicle, to a hitch arrangement of a towing vehicle. For tow bar applications wherein heavy, massive equipment is being moved a relatively short distance at very low speeds, such as where an airliner is being backed away from a terminal for example, the tow bar may have only one tow bar leg. For such applications, one end of the tow bar leg may be connected to the front end of the vehicle being moved and the other end of the tow bar leg connected to the front end of the moving vehicle so the operator of the towing vehicle can face the vehicle being moved and carefully observe the response of the trailing vehicle as it is being slowly moved by the towing vehicle.
For applications wherein the trailing vehicle is being towed at speeds other than very slow speeds, the tow bar generally has two tow bar legs, the front end of each tow bar leg being pivotally connected to a head of the tow bar. In use, the front ends of the tow bar legs form the apex of an isosceles triangle and the rear ends of the tow bar legs are spaced apart to form the sides of the isosceles triangle. The triangular configuration causes the trailing vehicle to closely track the towing vehicle both along straightaways and around corners.
Tow bars are generally designed to accommodate variations in attitude that inherently occur between the towing and trailing vehicles. One such variation in attitude between the vehicles occurs when the instantaneous elevation of the towing vehicle differs from the instantaneous elevation of the trailing vehicle. A related variation in attitude between the vehicles occurs when the instantaneous ascent/descent orientation of the towing vehicle differs from the instantaneous ascent/descent orientation of the trailing vehicle. Both of these related variations in attitude can be accommodated by tow bar apparatii designed to accommodate relative rotations between the towing and trailing vehicles about a transverse, horizontal axis, commonly referred to as the “pitch” axis, see the “z”-axis in FIG. 1.
Another such variation in attitude between the vehicles occurs when the instantaneous horizontal direction in which the towing vehicle is traveling differs from the instantaneous horizontal direction in which the trailing vehicle is traveling, such as when the trailing vehicle is being pulled around an unbanked corner for example. This situation, commonly referred to as “yaw”, can be accommodated by tow bar apparatii designed to accommodate relative rotations between the towing and trailing vehicles about a vertical axis, see the “y”-axis in FIG. 1.
Finally, another such variation in attitude between the vehicles occurs when the instantaneous sidewise tilt of the towing vehicle differs from the instantaneous sidewise tilt of the trailing vehicle, such as the rocking motions which occur when traversing uneven or rough pavement for example. This situation, sometimes referred to as “roll”, can be accommodated by tow bar apparatii designed to accommodate relative rotations between the towing and trailing vehicles about a longitudinal, horizontal axis, see the “x”-axis in FIG. 1.
During actual towing operations, all combinations of pitch, yaw and roll are continuously occurring and constantly changing between the towing and trailing vehicles. Prior art is replete with tow bar designs that have been developed in an attempt to accommodate these phenomena, some of those tow bar designs being more successful than others. For example, such designs include ball hitch/ball receiver combinations, conventional receiver hitch/square tube combinations, and pintle hitch/lunette ring combinations.
Most tow bars for towing a vehicle behind another vehicle have two tow bar legs pivotally connected to, and extending rearwardly from, a tow bar head. In order to simplify connection of the tow bar between the towing and trailing vehicles, each of the tow bar legs has an outer member and an inner member wherein the inner member is telescopingly displaceable longitudinally relative to the outer member. After the tow bar legs have been connected between the towing and trailing vehicles, the towing vehicle is slowly eased forwardly relative to the trailing vehicle to thereby extend each inner member outwardly from its respective outer member until the length of each tow bar leg reaches a predetermined length. Each tow bar leg generally has a latch which locks the inner member relative to its outer member at that predetermined length.
Prior art tow bar leg latches are typically mounted on each outer member and include a mechanism that interacts with only one side of the respective inner member. This arrangement may be practical when towing passenger-type, relatively light-weight vehicles. However, when towing massive vehicles, such as military or heavy construction vehicles, lateral forces operatively created in tow bar legs having such one-sided latches tend to cause the legs to bend and buckle, sometimes disastrously, because the legs are unable to endure the stresses arising from the extreme lateral forces which commonly occur when towing such massive vehicles, particularly when decelerating.
What is needed is a locking mechanism for a telescoping leg of a tow bar wherein the locking mechanism simultaneously interacts with opposing sides of the tow bar leg to more symmetrically distribute such extreme, adverse forces and thereby enable the tow bar legs to endure those lateral forces.